I am trying to be proactive about my engine maintenance. What is the consensus regarding the number of hours of run-time on a relatively new (2004) Yanmar 2GM20-F diesel engine, before I should be buying a spare exhaust elbow for installation?
Time for a new exhaust elbow?
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Maybe I'm missing something but I don't think I'd ever buy a spare. It's something to clean usually, not replace unless it somehow got cracked.
Maybe I'm missing something but I don't think I'd ever buy a spare. It's something to clean usually, not replace unless it somehow got cracked.
If it ain't broke....
While I think doing proactive maintenace is generally a good thing, I also believe in the old adage about leaving stuff alone if it isn't squeaking... I personally feel that an exhaust elbow's life depends on a lot of factors that may be hard to reduce to a number of years before replacement is necessary. How often you use your engine and for how long, how you use your engine in terms of rpms, the quality of fuel you use, etc., all play a role in the mean time between failure of various parts. What I do with my 20 year old 2GM20F is run the engine hard now and then, keep idle times to a minimum, motor between 2500 and 2700 rpm, and use the best quality fuel (with cetane booster, biocide, and stabilizer) -- and look for signs or indicators of trouble before routinely replacing anything but fuel and oil filters. I don't believe an elbow is going to coke up and shut you down without giving you a lot of warning beforehand -- and that is when I'd deal with the elbow.
While I think doing proactive maintenace is generally a good thing, I also believe in the old adage about leaving stuff alone if it isn't squeaking... I personally feel that an exhaust elbow's life depends on a lot of factors that may be hard to reduce to a number of years before replacement is necessary. How often you use your engine and for how long, how you use your engine in terms of rpms, the quality of fuel you use, etc., all play a role in the mean time between failure of various parts. What I do with my 20 year old 2GM20F is run the engine hard now and then, keep idle times to a minimum, motor between 2500 and 2700 rpm, and use the best quality fuel (with cetane booster, biocide, and stabilizer) -- and look for signs or indicators of trouble before routinely replacing anything but fuel and oil filters. I don't believe an elbow is going to coke up and shut you down without giving you a lot of warning beforehand -- and that is when I'd deal with the elbow.
The real issue is the weld on the nipple
rather than coking up. If you trust the weld will last forever, we need to visit the tooth fairy together. 543 hours average (?), many last a lot longer, some fail a lot sooner. When they go, they go at the worst possible time. Your boat, your choice.
rather than coking up. If you trust the weld will last forever, we need to visit the tooth fairy together. 543 hours average (?), many last a lot longer, some fail a lot sooner. When they go, they go at the worst possible time. Your boat, your choice.
Cleaning
I don't remember how many hours I had before I had trouble with the mixing elbo coking up so bad that the engine would not start one spring after winter lay up. I did clean it out and the engine ran so much better that I would take it apart every year and clean it out and it would really run so good,I guess maybe I was not noticing a difference rpm's or boat speed change before it gave me a problem. All I know is taking apart once a year was easy to do keeping it clean was easy also and the engine always ran great. It was nice to inspect it before it went bad. Nick
I don't remember how many hours I had before I had trouble with the mixing elbo coking up so bad that the engine would not start one spring after winter lay up. I did clean it out and the engine ran so much better that I would take it apart every year and clean it out and it would really run so good,I guess maybe I was not noticing a difference rpm's or boat speed change before it gave me a problem. All I know is taking apart once a year was easy to do keeping it clean was easy also and the engine always ran great. It was nice to inspect it before it went bad. Nick
For Stu... and other clock watchers....
FWIW, mine lasted 827 hours, 38 min, 14 sec....give or take a few nanoseconds. An "average time" for failure of an elbow? Give me a break. And coking WAS the problem when I replaced it. What kind of longitudinal data, other than your own, is that number based on? If you believe that number is correct, are you going to replace yours with a new one a few seconds before you hit 1,080 hrs on your clock? Whateve happened to common sense maintenance? Stuff lasts ... as long as it lasts. Who has the money or time to replace a lot of parts that are working just fine? Just pay attention to the signs and signals your boat is sending you and then fix it. I can't think of a thing that is fine one day, dead the next, and no signals being sent in between. Think of it terms of an angioplasty for your heart. Lots of signs and signals when it's time to get your tubes blown out.... same with your boat's arteries.
FWIW, mine lasted 827 hours, 38 min, 14 sec....give or take a few nanoseconds. An "average time" for failure of an elbow? Give me a break. And coking WAS the problem when I replaced it. What kind of longitudinal data, other than your own, is that number based on? If you believe that number is correct, are you going to replace yours with a new one a few seconds before you hit 1,080 hrs on your clock? Whateve happened to common sense maintenance? Stuff lasts ... as long as it lasts. Who has the money or time to replace a lot of parts that are working just fine? Just pay attention to the signs and signals your boat is sending you and then fix it. I can't think of a thing that is fine one day, dead the next, and no signals being sent in between. Think of it terms of an angioplasty for your heart. Lots of signs and signals when it's time to get your tubes blown out.... same with your boat's arteries.
Thanks gents for your inputs. We have 150 hrs on our engine, almost all of it going into/outof port, 40 minutes each sail, or motoring longer on the Ches. Bay on no wind days. All motoring is at 2500-2800 rpms, and idling at the pier is kept to a mininum. The reason for asking was that I perceived others on the forum occasionally having unexpected sudden onset of symptems, which, as a result, sometimes denied them power at times of need. We have never undertaken an elbow cleanout before, and perhaps were somewhat influenced by reported difficulties getting the elbow off of the engine exhaust system when it is glued on because of crud. We therefore were actually relying on the old maxim "If it ain't broke..........." The message I infer from your coments is that the elbow almost always can be removed and cleaned, if it hasn't been left on to corrode in place for years and years. Warren: We will take to heart your comments re cetane booster. We already use a stabilizer and biocide. Thanks
For us it was around 800 hrs.
When these fail it is usually not a catastrophic failure which means that most likely the engine will bring you back to the dock even if it is running poorly. I would not consider purchasing a spare mixing elbow unless I was doing a long cruise.
When these fail it is usually not a catastrophic failure which means that most likely the engine will bring you back to the dock even if it is running poorly. I would not consider purchasing a spare mixing elbow unless I was doing a long cruise.
WJSSR re cetane booster
In a recent post on ULSD fuel, I noted that it seemed most sellers were now selling ULSD fuel that had a cetane rating of 40. The Yanmar manual calls for a rating of 45. As a result, I add a bit of "Diesel Kleen" booster to each batch of diesel that I tennis shoe to the boat in jerry jug. Not sure it helps, but I don't think it hurts, either.
In a recent post on ULSD fuel, I noted that it seemed most sellers were now selling ULSD fuel that had a cetane rating of 40. The Yanmar manual calls for a rating of 45. As a result, I add a bit of "Diesel Kleen" booster to each batch of diesel that I tennis shoe to the boat in jerry jug. Not sure it helps, but I don't think it hurts, either.
Pete and Benny
1. Pete: There was a ? mark after the 543 hours. And the reminder of the statement mentioned that. BTW, we have been doing some checking with our 1800 Catalina 34s over the years and that's where the number comes from. I do my homework. The Yanmar elbow may be different, but our nipples are welded into the exhaust riser, and this is what those who have been reporting it tell us. Sorry if I keep records and share them. 2. Benny - I've been recommending that people check them regularly. Mine failed CATASTROPHICALLY and I had to sail four hours to get home (for a 1 1/2 hour motor). Many others have. A friend's died when outside the Golden Gate (no wind, lumpy seas - too lumpy for me to tow him) so he had Vessel Assist do it. I take it we're talking about the mixing elbow where the hot raw water mixes with the hot exhaust gases. I don't see how you can continue to run your engine with hot water and hot gases filling up the boat. So for those of you who are just waiting for it to go, Good Luck and God Bless. It takes some time for Catalina to make new ones, or you can make your own, but your boat will be out of service. Unplanned downtime is at least twice, if not more, annoying, than planned downtime during a sailing season.
1. Pete: There was a ? mark after the 543 hours. And the reminder of the statement mentioned that. BTW, we have been doing some checking with our 1800 Catalina 34s over the years and that's where the number comes from. I do my homework. The Yanmar elbow may be different, but our nipples are welded into the exhaust riser, and this is what those who have been reporting it tell us. Sorry if I keep records and share them. 2. Benny - I've been recommending that people check them regularly. Mine failed CATASTROPHICALLY and I had to sail four hours to get home (for a 1 1/2 hour motor). Many others have. A friend's died when outside the Golden Gate (no wind, lumpy seas - too lumpy for me to tow him) so he had Vessel Assist do it. I take it we're talking about the mixing elbow where the hot raw water mixes with the hot exhaust gases. I don't see how you can continue to run your engine with hot water and hot gases filling up the boat. So for those of you who are just waiting for it to go, Good Luck and God Bless. It takes some time for Catalina to make new ones, or you can make your own, but your boat will be out of service. Unplanned downtime is at least twice, if not more, annoying, than planned downtime during a sailing season.
Stu and Ross, Pt II
Stu: Of course, anything can fail catastrophically, but in good quality products, that are used and maintained properly, they usually do not. Of the 25,369 Yanmar owners I've been keeping track of since 1908, none have failed at the 543 hour mark
. I think that if you have 1800 Cat 34 owners with this problem, you have all the makings for a class action suit against whoever makes your engines. Then again, perhaps you all can now buy your replacement elbows in bulk and all replace them at the 542 hour mark....make a weekend family event out it. Ross: I keep hearing all the anecdotal tales about using veggie oil in diesels. Why don't we pour some in your diesel and see how it likes it? Maybe we could get some left over oil from the fryer at Mickey D's and put that into your engine?
Stu: Of course, anything can fail catastrophically, but in good quality products, that are used and maintained properly, they usually do not. Of the 25,369 Yanmar owners I've been keeping track of since 1908, none have failed at the 543 hour mark
. I think that if you have 1800 Cat 34 owners with this problem, you have all the makings for a class action suit against whoever makes your engines. Then again, perhaps you all can now buy your replacement elbows in bulk and all replace them at the 542 hour mark....make a weekend family event out it. Ross: I keep hearing all the anecdotal tales about using veggie oil in diesels. Why don't we pour some in your diesel and see how it likes it? Maybe we could get some left over oil from the fryer at Mickey D's and put that into your engine?Some observations
1. The question is a good one, seriously presented. 2. Some elbows inexplicably fail at spring launch. 3. Acid cleaning will remove coke, but internal damage to the cast iron could lead to pinhole leaks. Better to replace anew. 4. People report better performance with new elbows. 5. I cut my cetane back from 48 to 44 to reduce smoke. 6. Run hot but not too hot or more smoke will build up. 7. Disregard the rant of the nanosecond sarcasm. Boys will be boys.
1. The question is a good one, seriously presented. 2. Some elbows inexplicably fail at spring launch. 3. Acid cleaning will remove coke, but internal damage to the cast iron could lead to pinhole leaks. Better to replace anew. 4. People report better performance with new elbows. 5. I cut my cetane back from 48 to 44 to reduce smoke. 6. Run hot but not too hot or more smoke will build up. 7. Disregard the rant of the nanosecond sarcasm. Boys will be boys.
Class action NOT
Pete, it's an add-on to the exhaust of a tractor engine for marine use in M25 engines, which are Kubota blocks. They are a simple piece of material (NOT equipment) that DO fail, much like replacing a muffler or exhaust pipe on a car. Perhaps I again missed your point about anticipated "time of failure", but as someone once said: "Your use may vary..." Regardless of the "exact" timing, they DO need to be replaced, at least on our engines. I wrote an account of the failure and replacement in a Mainsheet Tech Notes article a few years ago. The point is that they can and do fail, and it is NOT a manufacturing mistake, it's the way it is. People have a wide variety of replacement options, from "made for you by Catalina" to making up their own from Schedule 80 or Schedule 40 pipe, stainless, galvanized or black iron. It happened to me, and many others, and is among a series of topics covered in great detail on our C34 website. Some of our boats are over 21 years old now, and could be on their third or fourth riser replacement based on engine use. The BULK order idea is a really good one - thanks for the concept.
Pete, it's an add-on to the exhaust of a tractor engine for marine use in M25 engines, which are Kubota blocks. They are a simple piece of material (NOT equipment) that DO fail, much like replacing a muffler or exhaust pipe on a car. Perhaps I again missed your point about anticipated "time of failure", but as someone once said: "Your use may vary..." Regardless of the "exact" timing, they DO need to be replaced, at least on our engines. I wrote an account of the failure and replacement in a Mainsheet Tech Notes article a few years ago. The point is that they can and do fail, and it is NOT a manufacturing mistake, it's the way it is. People have a wide variety of replacement options, from "made for you by Catalina" to making up their own from Schedule 80 or Schedule 40 pipe, stainless, galvanized or black iron. It happened to me, and many others, and is among a series of topics covered in great detail on our C34 website. Some of our boats are over 21 years old now, and could be on their third or fourth riser replacement based on engine use. The BULK order idea is a really good one - thanks for the concept.
Run um hard all the time
Yet another reason to run your little diesel pony hard ALL the time. As far as I can tell there is no reason to go slower than 95% throttle. Getting there later is not an excuse, nor is saving the engine. I could go on and on about my experiences with diesels that where idled to death or never taken out and run hard and died young.
Yet another reason to run your little diesel pony hard ALL the time. As far as I can tell there is no reason to go slower than 95% throttle. Getting there later is not an excuse, nor is saving the engine. I could go on and on about my experiences with diesels that where idled to death or never taken out and run hard and died young.
Exhaust elbow replacement
For a 2GM20F, 1991 vintage you should at least remove and clean the exhaust elbow. It consists of four pieces and there isn't room to take them apart on the engine; remove them as one: 1. An upright elbow is welded to a flange plate which is bolted to the rear of the exhaust manifold with four bolts. 2. A right hand-left hand stainless steel threaded connector joins the elbow to the 'U' shaped cast iron water injection elbow. It is fairly thin material. 3. The 'U shaped cast iron injection elbow has two side by side chambers; 4. one of which has a brass 'nipple' for connecting the inlet water line; The bottom side of the 'U' connects to the flexible exhaust hose. Use PB Blaster and small screw drivers to separate the two without tearing the hose. Once the hot side of the 'U' is coked up it is difficult but not impossible to clean with comercial grade wire brush fittings on a drill and/or a small chisel; the other three pieces are relatively easy to clean and reassemble with anti-seize sealant. I wouldn't use acid as it could create pinhole leaks in the cast iron. Put the metal components back together and bolt to the back of the manifold with a new gasket after scraping off all the old material.
For a 2GM20F, 1991 vintage you should at least remove and clean the exhaust elbow. It consists of four pieces and there isn't room to take them apart on the engine; remove them as one: 1. An upright elbow is welded to a flange plate which is bolted to the rear of the exhaust manifold with four bolts. 2. A right hand-left hand stainless steel threaded connector joins the elbow to the 'U' shaped cast iron water injection elbow. It is fairly thin material. 3. The 'U shaped cast iron injection elbow has two side by side chambers; 4. one of which has a brass 'nipple' for connecting the inlet water line; The bottom side of the 'U' connects to the flexible exhaust hose. Use PB Blaster and small screw drivers to separate the two without tearing the hose. Once the hot side of the 'U' is coked up it is difficult but not impossible to clean with comercial grade wire brush fittings on a drill and/or a small chisel; the other three pieces are relatively easy to clean and reassemble with anti-seize sealant. I wouldn't use acid as it could create pinhole leaks in the cast iron. Put the metal components back together and bolt to the back of the manifold with a new gasket after scraping off all the old material.
exhaust elbow
I have a 1999 3GM30 Yanmar that needed the exhaust elbow replaced in 2004. I think at that time it had less than 200 hours. I found someone to weld it and it has lasted until now. But it does need to be replaced again. This is a Catalina part. So I think it varies on when it needs replaced.
I have a 1999 3GM30 Yanmar that needed the exhaust elbow replaced in 2004. I think at that time it had less than 200 hours. I found someone to weld it and it has lasted until now. But it does need to be replaced again. This is a Catalina part. So I think it varies on when it needs replaced.
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